Attachment for a hand-held power tool

ABSTRACT

An attachment for at least rotary hand-held power tool includes a tool holder ( 13 ) for receiving a working tool and extending into the power tool outer housing ( 12 ), a coupling section ( 14, 34 ) for connection with a drive shaft ( 2 ) of the at least rotary hand-held power tool ( 1 ), and a ventilation device arranged in the outer housing ( 12 ).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an attachment for a hand-held power tool and which includes an outer housing, a tool holder for receiving a working tool, and a coupling section for connection with a drive spindle of the hand-held power tool that can be formed at least as a rotary power tool.

2. Description of the Prior Art

With attachments of the type described above, the application range of hand-held power tools such as at least rotary power tools can be noticeably widened. The attachment, such as, e.g., a tool holder, includes a coupling section with which it can be mounted on the drive spindle of at least rotary power tool. The tool holder includes, e.g., a chuck, such as a standard three-or-two-jaw chuck which is formed for receiving a corresponding shank of a drill, percussion drill, borer, or chisel. In this way, different working tools, which may have different types of shanks, can be secured on one and the same hand-held power tool. The attachment can further be formed as an angle drilling attachment, as a screw-driving attachment, as a thread-cutting attachment, ets., and is mounted on the drive spindle of a power tool, e.g., at least rotary power tool.

German Publication DE 35 15 661 A1 discloses different attachments having a coupling section with which they are mounted on a drive spindle of a rotary percussion power tool. The drawback of the attachment according to DE 35 15 661 A1 consists in that during operation, high temperatures can be produced in the outer housing of the attachment. As a result, these attachments can be used, without cooling, only for a limited time. In the worst case, a thermal breakdown can occur during an operation. This is particularly the case in angle drilling attachments in which losses, which results from deflection, are additionally converted into heat.

German Publication DE 196 26 254 A1 discloses feeding cooling air from a hand-held power tool to an attachment, which is formed as a tool holder, through axial passage slots. The drawback of this solution consists in that the cooling air becomes very heated as a result of cooling the motor, the gear drive, and the percussion mechanism, and the tool holder cannot be adequately cooled by the heated outgoing air. In addition, the tool holder forms an additional resistance for the air flow of the power tool which leads to an additional load being applied to ventilation elements of the power tool which, in turn, can lead to their damage during a lasting operation.

Swiss patent CH 692 488 A5 discloses a hand-held power tool with an attachment and in which the outlet openings in the power tool housing are closed with guide elements, so that the outgoing, from the power tool, air is conducted through a cooling channel to the to-be-cooled working tool region of the attachment. The drawback of this solution consists in that a pre-heated cooling air is used and in that the guide elements additionally load the power tool.

SUMMARY OF THE INVENTION

An object of the present invention is to insure an adequate cooling of a rotatable attachment even during a lasting operation, without noticeably additionally loading the ventilation elements of the power tool.

These and other objects of the present invention, which will become apparent hereinafter, are achieved by providing a ventilation device in the outer housing of the attachment. The ventilation device is driven, directly or indirectly, by the drive spindle of the power tool, so that a cooling air flow is produced within the attachment. The ventilation device inside the attachment housing reduces the temperature in the attachment and increases the operating time of the attachment during a lasting operation. The ventilation elements of the power tool are responsible for cooling of only the power tool and are not additionally responsible for cooling the attachment and, therefore, should be designed accordingly.

Advantageously, at least one outlet opening for releasing of the cooling air from the attachment is provided in the outer housing, e.g., in the region of the attachment remote from the power tool. Thereby, the cooling flow, which is produced by the ventilation device, flows through the attachment, removing the heat produced in the attachment.

Advantageously, at least one inlet opening for admitting surrounding air, which is aspirated by the ventilation device, is provided in the outer housing of the attachment. Thus, there is produced an air flow for cooling of the attachment and which is not pre-heated in the power tool. A separate cooling air flow for the attachment, independent of the cooling air flow in the power tool, insures an extended operational time of the attachment also during its lasting operation.

Preferably, the ventilation device for producing a cooling air flow in the attachment includes at least one rotatable blower wheel. Dependent on the need in cooling of the attachment, for producing of the necessary cooling flow more than one blower wheel can be provided in the attachment.

Advantageously, the at least one blower wheel is mounted on the coupling section of the attachment for joint rotation therewith. The cooling air flow is, thereby, produced by the at least one blower wheel in the region of the attachment adjacent to the power tool, and can flow through the entire outer housing of the attachment for cooling the same. For fixedly mounting the blower wheel on the coupling attachment for joint rotation therewith, the blower wheel is, e.g., pressed onto the coupling section or is glued thereto. When the blower wheel is formed of a plastic material, it can be, e.g., shrinked over the coupling section.

Advantageously, the attachment includes a further drive shaft with, advantageously, a further blower wheel mounted thereon. The additional or further drive shaft can serve, e.g., for driving a chuck of an angle drilling attachment. The at least one blower wheel can, e.g., be pressed on further drive shaft or be shrunk thereon in case the blower wheel is made of a plastic material. When more than one blower wheel is used then, e.g., one blower wheel is mounted on the coupling section, and the further blower wheel is mounted on the further drive shaft in a region of the shaft further remote from the power tool.

The novel features of the present invention, which are considered as characteristic for the invention, are set forth in the appended claims. The invention itself, however, both as to its construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of preferred embodiments, when read with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings show:

FIG. 1 a longitudinal cross-sectional view of an angle drilling attachment according to the present invention which is mounted on an hand-held power tool; and

FIG. 2 a longitudinal cross-sectional view of a tool holder which forms an attachment according to the present invention and is mounted on a hand-held power tool.

In both embodiments, the same elements are designated with the same reference numerals.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

An attachment 11 according to the present invention, which is shown in FIG. 1 and is formed as an angle drilling attachment for at least rotary hand-held power tool 1 such as, e.g., electro-pneumatic hammer drill, includes an outer housing 12, a tool holder 13 for a working tool such as a drill or a hammer or percussion drill. The attachment 11 further includes a coupling section 14 connectable with a drive spindle 2 of the power tool 1. For driving a working tool receivable in the tool holder 13, there is provided, on the coupling section 14, a two-part drive shaft 15, 16 which is arranged in the outer housing 12.

A ventilation device for the attachment includes two rotatable blower wheel 17, 18. The first blower wheel 17 is mounted on the coupling section 14 for joint rotation therewith. The second blower wheel 18 is mounted on the drive shaft 15 likewise for joint rotation therewith. In the outer housing 12, there is provided an inlet opening 21 for admitting the surrounding air and a plurality of outlet openings 22 for releasing a cooling stream 23 produced by the blower wheels 17, 18. Instead of two blower wheels 17, 18, only one blower wheel can be provided which can be mounted either on the coupling section 14 or the drive shaft 15.

An attachment 31, which is shown in FIG. 2, is formed as a tool holder for receiving a drill, a percussion drill, or a chisel. For cooling, the attachment 31 has a ventilation device that is formed by a blower wheel 37 mounted on the coupling section 34.

Though the present invention was shown and described with references to the preferred embodiments, such are merely illustrative of the present invention and are not to be construed as a limitation thereof and various modifications of the present invention will be apparent to those skilled in the art. It is, therefore, not intended that the present invention be limited to the disclosed embodiments or details thereof, and the present invention includes all variations and/or alternative embodiment within the spirit and scope of the present invention as defined by the appended claims. 

1. An attachment for at least a rotary hand-held power tool, comprising a outer housing (12); a tool holder (13) for receiving a working tool and extending into the outer housing (12); a coupling section (14, 34) for connection with a drive shaft (2) of the at least rotary hand-held power tool (1); and a ventilation device arranged in the outer housing (12).
 2. An attachment according to claim 1, wherein at least one outlet opening (22) is provided in the outer housing (12).
 3. An attachment according to claim 1, wherein at least one inlet opening (21) is provided in the outer housing (12).
 4. An attachment according to claim 1, wherein the ventilation device comprises at least one rotatable blower wheel (17, 18; 37).
 5. An attachment according to claim 4, wherein the blower wheel (17, 37) is mounted on the coupling section (14, 34) for joint rotation therewith.
 6. An attachment according to claim 1, further comprising, in addition to the coupling section (14), a further drive shaft (15).
 7. An attachment according to claim 6, wherein the ventilation device comprises two blower wheels (17, 18) mounted, respectively, on the coupling section (14) and the further drive shaft (15). 